Catalytic highly enantioselective 1,3-dipolar cycloaddition reaction of nitrones with 3-alkenoyl-2-oxazolidinones by use of a bidentate chiral bis(imine) ligand–Cu(II) triflate complex
摘要:
A copper(II) triflate complex with bidentate, chiral C-2-symmetric cyclohexane-1,2-bis[(2,6-dichlorophenylmethylene)amine] catalyzed the 1,3-dipolar cycloaddition reactions of nitrones with electron-deficient dipolarophiles, 3-(2-alkenoyl)-1,3oxazolidin-2-ones to give isoxazolidine cycloadducts with extremely high endo- and en antio selectivities. (C) 2004 Elsevier Ltd. All rights reserved.
of a chiral C2-symmetric bis(oxazoline) ligand, its Lewis acid complexes-catalyzed asymmetric 1,3-dipolarcycloaddition reactions of nitrones with electron-deficient dipolarophiles, 3-(2-alkenoyl)-1,3-oxazolidin-2-ones, have been investigated and it was found that the cycloadditions using a Cu(II)-bis(oxazoline) complex under optimized reaction conditions induced extremely high enantioselectivity.